Known switched-mode power supplies comprise, e.g., the following functional units: a rectifier for rectifying an input AC voltage, a filter circuit for filtering the rectified input AC voltage, a switching unit with a downstream-connected transformer, a further rectifier circuit with a filter circuit and if necessary a regulator mechanism. The regulator mechanism improves the efficiency of the switched-mode power supply by controlling, e.g., the impulse width of the clock signal and by thus adapting the energy intake to the energy consumption using a power factor corrector (PFC). The switching frequency can be relatively high, e.g., between 25 kHz and 500 kHz, or even higher. As a result, the transformer, which provides not only the transformation but also an electrical isolation, can be relatively small and easily implemented. The switching function itself is implemented with, e.g., transistors, more particularly MOSFETs, or thyristors, e.g., using pulse width modulation.